1. Field of the Invention
The present invention relates to an impeller in which a metallic bush can be inserted correctly into a synthetic resin impeller main body manufactured by resin molding using a die, and a determination as to whether or not the impeller has been manufactured correctly can be made easily.
2. Description of the Related Art
Conventionally, a pump such as a water pump is provided with an impeller constituted by a resin impeller main body portion formed with a plurality of vanes, and a metallic bush portion serving as a boss for supporting a drive shaft. Most of these impellers are formed by resin molding using a die. Japanese Unexamined Patent Application Publication 2003-3991 exists as an example of an impeller product formed by molding resin using a die and a core member.
In the invention described in Japanese Unexamined Patent Application Publication 2003-3991, a metallic boss is inserted in and attached to a V-shaped bulging portion of an impeller main body such that the V-shaped bulging portion on the impeller main body side can be formed in a compact shape, the thickness of the V-shaped bulging portion can be secured adequately, and the metallic boss can be attached to the impeller main body extremely securely.
One axial end side of the metallic boss portion takes a truncated cone shape, while the other axial end has anon-circular outer periphery to prevent idle rotation.
A throttle portion having a truncated cone shape is formed on the metallic boss. By inserting this part into the tip end of the V-shaped bulging portion on the impeller main body, the V-shaped bulging portion can be provided with an appropriate thickness corresponding to the throttle portion, and a sufficient dynamic strength can be secured without making the V-shaped bulging portion on the periphery of the inserted throttle portion of the metallic boss excessively thick. Thus, the impeller can be reduced in size.